2, transition, open the following. The "turning point of Darwin's life" you mentioned at the beginning of "Sometimes, an accidental event will affect one's life choice" is such a nature. Starting with a famous saying similar to Darwin's life experience, on the one hand, it leads to an introduction to Darwin, on the other hand, it summarizes Darwin's life from a certain aspect. 1, if it is a turning sentence, people will connect the front with the back.

Lead to the following situation

What is the function or purpose of the key sentences at the beginning of the article?

For example, what is the purpose of the sentence "Sometimes, an accidental event will affect a person's life choice" written by the author at the beginning of Darwin's turning point in life?